Blood pressure measuring apparatus



May 24, 1966 w. w. HAY

BLOOD PRESSURE MEASURING APPARATUS ,2 Sheets-Sheet 1 Filed Oct. 18, 1962 ARMLET INVENTOR.

HAY

WAYNE W.

AGENT May 24, 1966 w. w. HAY

BLOOD PRESSURE MEASURING APPARATUS g Sheets-Sheet 2 Filed Oct. 18, 1962 FlG. 4

51F IG. lo.

United States Patent 3,252,459 BLOW) PRESSURE MEASURING APPARATUS Wayne W. Hay, Madison, Wis., assignor to Air Reduction Company Incorporated, New York, N.Y., a corporation of New York Filed Oct. 18, 1962, Ser. No. 231,336 4 Claims. (Cl. 1282.05)

This invention relates to blood pressure taking apparatus. While not limited thereto, it has especial utility in such apparatus intended for use during anesthesia; it will, accordingly, be described primarily with reference to such use.

The invention, contemplating that the observation of the patients pulse will itself be made in a conventional manner, is concerned with the apt development and release of the pressure in an inflatable pressure-transmitting member, typically an armlet or cuff, which itself will be secured conventionally to the patient,

In the typical use of blood pressure taking apparatus during anesthesia, the anesthetist is occupied with various ramifications of the proper administration of the anesthetic, of which recurrent observation of the patients blood pressure is only one. It is, accordingly, of great importance that the attention and effort required of him for the blood pressure observation be as much as possible minimized. On the other hand, it is desirable that the development and release of pressure in the inflatable member take place only when the anesthetist actually intends to make a blood pressure determination, and even then with as much dispatch as reasonably possible, in order that the patients circulation be interfered with to a minimum extent.

According to a broad aspect of the invention, the pressure in the inflatable member is developed, from a pressurized source of gas (conveniently a source already present for use in the anesthesia proper), and then released in a single automatic cycle which may be invoked at any time and from time to time by the anesthetist and which sequentially comprises a rapid rise of the pressure to a preadjusted over-systolic value, a release of the pressure at a slow pre-adjusted rate to a pre-adjusted under-diastolic value, and a moderate-rate release to zero. The onset of the first such part of the cycle is under the command of the anesthetist, while the onsets of the second and third parts are automatic, under the control of the pressure in the inflatable member.

According to another aspect of the invention, concerned simply with the first two parts of the cycle above-mentioned, there is provided an actuator available for a displacement by the anesthetist by which there is opened the path through which gas from the source flows rapidly into the inflatable member, together with means controlled by the pressure within that member for restoring the actuator and thus closing the inlet path when the member pressure has risen to a predetermined value, and with a bleed path for the slow bleeding away of that pressure at least after the inlet path is closed. According to a more specific aspect of the invention, the actuator may be provided with a latching arrangement appropriate to the action just described.

Specific features of the invention provide for widerange adjustability of the value to which the pressure will rise, for the relief of excess pressures which might tend to develop as a result of maladjustment or the like, for the connection of the conventional blood-pressure hand bulb for pressure variations superimposed on or alternative to those of the automatic cycle, and for various other actions hereinafter described.

Important objects of the invention have been made apparent by the foregoing brief description. It is a further 3,252,459 Patented May 24, 1966 objective to achieve those objects by apparatus which is simple, reliable, safe and inexpensive. Allied and other objects will be made apparent in the following detailed description and the appended claims.

In the detailed description of the invention hereinafter set forth, reference is had to the accompanying drawings, in which:

FIG. 1 is a schematic view of the armlet or cuff and of the manometer of typical blood-pressure-taking apparatus and of a pressurized source of gas, together with a relatively much-enlarged vertical cross-sectional view of an associated control device, seen in readiness for actuation, according to the invention;

FIG. 1a is a view similar to a part of the cross-sectional portion of FIG. 1 but illustrating the components in the positions they have assumed just after actuation;

FIG. 2 is a plan view of the control device, in which the line 11 indicates the plane along which the cross-' sectional portion of FIG. 1 is taken;

FIG. 3 is a horizontal cross-sectional view taken along the line 33 of FIG. 1;

FIG. 4 is a view whose upper portion is an elevational showing of the control device and whose lower portion is a vertical cross section taken along the line 44 of FIG. 2 and illustrating its components in readiness for actuation;

FIG. 5 is a fractional vertical cross-sectional view taken along the line 5-5 of FIG. 2; and

FIG. 6 is a perspective view of the control device showing its desirable mounting to one of the corner posts of an anesthesia machine.

Reference being had to FIG. 1, there will be seen a conventional manometer 1 (typically of the mercurycolumn type) connected as by tubing 2 to a socket 4 into which there may beplugged a tubing 5 connected to an inflatable pressure-transmitting member or armlet 7 which may be the armlet or cuff conventional in bloodpressure-taking apparatus. When the invention is used in connection with an anesthesia machine, the socket 4 may conveniently be mounted at a readily accessible position on that machine. The tubing 5 may be provided with a tap or T 6 to which may be connected a hand bulb 8 of the type conventional in blood-pressure-taking apparatus (being accordingly provided with check valves, not shown, arranged to permit only ingress of ambient air into the bulb and from the bulb only egress of air into the immediately associated tubing), which, of course, is provided with a regulable bleed valve 9 operatively leading from the immediately associated tubing to the ambient air. It is to be understood, as will hereinafter more fully appear, that the bulb 8 and its bleed valve 9 are auxiliary devices only and may be omitted (the T 6 then being omitted or its side orifice closed).

The tubing 2 may be provided with a T 3 to which there is connected a line 10 leading from a tank 13 of gas, which may be air, oxygen or any other convenient and safe gas; when the invention is used in connection with an anesthesia machine, this tank may conveniently be the same tank as forms the source of one of the gases used in the anesthesia. At its outlet the tank 13 may, if desired, be provided with a conventional pressure-reducing means 12 to avoid excessive pressures in the adjacent portion of the line 10, the tank and that means (if employed) constituting a typical pressurized source 11 of gas.

The line 10 forms a passage connecting the source 11 on the one hand to the armlet 7 (and manometer 1) on the other. A control device 24] is interposed in the line 10. While the specific configuration and arrangement 21 may be machined from appropriately sized hexagonal stock, of metal such for example as brass.

Transversely through the lower portion of the housing 21, from one to the opposite one of the six faces,

there may be provided a medium-diameter bore 36 of which each end is .internally threaded. The right-shown portion of the bore 36 is effectively closed in manner hereinafter described; into the left-shown portion of the bore there may be screwed an adapter 19 to which the sourceward portion of the line .10 (which portion may be of semi-rigid tubing appropriate to the output pressure of the source 11) may be connected by suitable means not herein necessary to show. The top portion of the housing 21 (which may, if desired, be machined externally to cylindrical shape) is provided with a vertical bore 39 of a large diameter which is only a little less than the external diameter of that portion, the upper part of the bore 39 being internally threaded, and for a short distance downwardly from the bottom of the bore 39 there may coaxially extend a somewhat smallerbut still large-diameter bore 38. :From the bottom of the bore 38, for example close to its periphery, to the top of the left-shown portion of the bore 36 at a point free of the adapter 19, there may be provided a small-diameter vertical bore 37. Across the bottom of the bore 39 there may extend a diaphragm 41, corrugated near its periphery, that periphery being clamped in manner hereinafter described.

The left-shown portion of the horizontal bore 36 to the right of the adapter 19, the vertical bore 37, the vertical bore 38 and so much of the vertical bore 39 as may at any time lie below the diaphragm 41 may be considered as forming a chamber 40 of which the diaphragm forms a movable wall. From this chamber, specifically from the bore 38 in a nonaxial plane, there may be provided a horizontal port 22 (see FIGS. 1 and 2, in each of which this port appears dottedly); this port may be suitably shaped to form an externally available socket into which a suitable plug (not shown) on the end of the armletward portion 10" of the line 10 may be plugged, thereby placing the armlet 7 (and the manometer) in communication with the chamber 40. It will, accordingly, be understood that so long as the line portion 10 is plugged into the socket 22, the pressure which may from time to time exist within the chamber 40 and the pressure within the armlet 7 will for all practical purposes be the same.

For the admission of gas from the source 11 into the chamber 40 and thus into the armlet 7, a valve may be carried by the adapter 19 in an axial bore 18 through the latter which near its right-shown extremity may have a tapered portion 18 and which to the right of that portion may be internally threaded. Leftwardly into the bore 18 there may be screwed a valve 14, of the general type commonly used for the retention of air in (and its controllable release from) automobile tubes or tires, having intermediately along its length a tapered surface which will be securely seated against the tapered portion 18' of the bore 18. This valve has an axially disposed and axially movable stem 15 carrying a closure member 16 near its left-shown extremity and biased rightwardly, by internal means not necessary to show, to bring the closure member 16 normally into valve-closing abutment against the body portion 17 of the valve; when the stem 15 is moved leftwardly against its bias, however, it will carry the closure member 16 leftwardly away from the body portion 17 thereby to render terminally open an internal passage (not shown) through the valve and thus to establish communication between the bore 18 and the chamber 40. The bore 18 in the outer or left-shown portion of the adapter may have a local constriction 18" suitably to throttle the flow of gas from the line portion 10' into the chamber 40.

For the opening of the valve 14 thereis provided an actuator designated generally as 30 and of which the active portion is a plunger 32 whose left-shown portion fits and is axially movable within the right-shown portion of the horizontal bore 36. To retain the plunger 32 in this disposition, there may be screwed into the right-shown end portion of the bore 36 a bushing 29 through which the right-shown portion of the plunger, reduced in diameter for the purpose, extends outwardly (as shown, rightwardly). At its left-shown end the plunger 32 may be provided with a wide central recess 28 and within this recess may be disposed one end of a helical compression spring 27 whose other end surrounds the right-shown end portion of the adapter 19 (which is reduced in diameter for this purpose as well as to insure communication between bores 36 and 37) and bears against the adapter. The spring 27 biases the plunger 32 outwardly (as shown, rightwardly), response to that bias being limited and a norm-a1 plunger position established by impingement, against the inner end of bushing 29, of the shoulder between the leftand right-shown portions of the plunger. In that normal position of the plunger, illustrated in FIG. 1, the face of its recess 28 is minutely spaced from the end of the valve stem 15 with the valve 14 in closed condition.

Midway in its left-shown portion the plunger 32 may be provided with a circumferential groove 33 in which is disposed a rubber O-ring 34 which insures a seal between the plunger and the bore 36. Between the groove 33 and the left-shown end of the plunger there may be provided in the plunger another circumferential groove 35 hereinafter referred to. About the outer or rightshown portion of the plunger there may be secured an actuator knob 31, recessed if desired so as largely to cover the head portion of the bushing 29. It will be understood that if the actuator knob 31 be pressed for an appreciable distance inwardly (as shown, leftwardly) the plunger will be displaced in that direction and the valve 14 will be opened, and that as long as that displacement is maintained the valve 14 will be held open.

Attention may now be directed to the diaphragm 41 and the components associated therewith. The element which immediately clamps the diaphragm' periphery may be a relatively deep inverted cup-shaped member 42 whose downwardly directed mouth comprises an annular portion 44 joined to the smaller-diameter main portion of the member 42 by a washer-like portion 43 integral with both. The bottom edge of the portion 44 is caused to press the diaphragm periphery firmly against the shoulder formed between bores 38 and 39 by a clamping ring 46 which surrounds the main portion of the member 42 and whose lower portion is externally threaded and screwed into the upper part of the housing 21 to bear against the portion 43 of member 42. 1

The upwardly disposed bottom of the cup-shaped member 42, which may be relatively thick, is provided with a relatively large-diameter internally threaded bore into which (for example, from inside the member 42) is screwed a generally cylindrical adjustor 50 whose upper portion protrudes above the member 42 and which is provided with a bore 49 of substantial diameter extending upwardly from its bottom extremity. Extending upwardly into this bore is a plunger 51 formed at its lower end into a flange 52 whose bottom is shaped to fit against the top of the diaphragm 41 and whose diameter is sufficiently smaller than that of the member-portion 44 to leave free a substantial corrugated portion of the diaphragm. The central portion of the diaphragm may be held against the bottom of the flange 52 by a suitably surfaced washer-like element 54 and a nut 55 therebelow, both element 54 and nut 55 being disposed about a stud 56 whose upper portion is threaded to receive that nut and to extend upwardly into a threaded bore 53 formed in the lower portion of the plunger 51 coaxially with that plunger.

From the bottom of the vertical bore 38 to the top of the horizontal bore 36, and coaxial with the bores 38 and 39, there is provided in the housing 21 a bore 58 into which the unthreaded lower portion of the stud 56 extends. At its lower end that stud is provided with a reduced-diameter short end portion 57. Between the bottom of the adjustor 50 and the top surface of the plungers flange 52 there is provided about the plunger 51 a helical compression spring 59 which biases the plunger and thus the diaphragm downwardly. A small port 45 through the wall of the member 42 and a similar port 48 from the bore 49 of the adjustor 50 may serve to insure that the bias imparted to the diaphragm by the spring 59 will not be altered by the effect of air which might otherwise be trapped within the member 42 or the bore 49.

By the adjustor 50 the net downward bias on the diaphragm (which will, of course, be contributed to by any constraint developed in the diaphragm itself) may be variously established, but it is contemplated that that net bias will inany case be sufficient so that, in the absence of pressure (over-atmospheric) on the bottom surface of the diaphragm, the stud will be strongly enough urged downwardly so that the entirety of its end portion 57 will attempt to project into the horizontal bore 36. Accordingly, when the actuator 30 is in its normal position (as illustrated in FIG. 1) the stud end portion 57, in response to the net bias just mentioned, will bear downwardly against the full-diameter left-shown end portion of the actuator plunger 32.

The position of the circumferential groove 35 longitudinally of the actuator plunger 32 is so fixed that it will he 7 under the end portion 57 of the plunger 56 when the actu the valve 14. It will now be understood that when, in

the absence of pressure (over-atmospheric) on the bottom surface of the diaphragm 41, the actuator is sufficiently displaced inwardly, the end portion 57 of the plunger 56 will be projected downwardly, under the influence of the above-mentioned net bias on the diaphragm into the groove as illustrated in FIG. 1a. Now the presence of the plunger end portion 57 in the groove 35 will preclude any substantial further inward displacement of the actuator 3t), and on the other hand will prevent an outward movement of the actuator to its normal position; thus, the vertical-plunger end portion 57 and the groove 35 in the horizontal plunger 32 together form a means for latching the actuator in valve-opening position.

As a result of the open condition of the valve 14, gas

under pressure will flow from the source 11 into the chamber 40 and, thus, into the armlet 7; that flow will result in a progressive rise of the pressure within that chamber and that member. When that pressure has risen to a value sufiicient so that the upward force exerted by it on the diaphragm 41 exceeds the net downward bias on the diaphragm by an amount sufiicient to overcome the static frictions between the left-shown sides of the stud projection 57 and of the groove 35 and between the right-shown sides of the stud 56 and of the bore 37 (both resulting from the actuator bias), the diaphragm will move upwardly; when it has reached its initial position, illustrated in FIG. 1, the actuator will be unlatched and will forthwith assume its normal position (likewise illustrated in FIG. 1) in response to its bias. This will, of course, result in prompt closure of the valve 14, with a resulting cessation of pressure increase within the chamber 40 and armlet 7 and of the upward movement of the diaphragm 41.

The pressure-increasing infiux of gas into the chamber 46 and armlet 7, which by proper establishment of the diameter of the constriction 18" is made a rapid one, constitutes the first portion of a cycle whose next-ensuing portion is a slow decrease of the pressure within that chamber and that member. Such a decrease may be effected by a bleed path open, for the slow bleeding-way (for example, to the ambient) of gas from within that chamber and that member, at least after the return of the actuator 30 to normal position and the attendant closure of the valve 14. Since the rapid influx of gas into the chamber and inflatable member through the then-open valve will in rate far over-shadow this slow bleeding-away or efflux, it is permissible that the bleeding-away take place not only after the actuator return and valve closure, but also while the actuator is in its displaced position and the valve 1 4 is open, and in general this permits a simpler arrangement. The inward extremity 61 of a bleed path 60 of such simpler arrangement is illustrated in FIG. 1, and the entirety of that path is illustrated in FIG. 3.

Thus, at a level intermediate the extremities of the vertical bore 37, in a plane intersecting the axis of that bore, the housing 21 may be provided with a horizontal bore 62 leading inwardly, for example from one of its six faces other than those intersected by the horizontal bore 36, into intersection with the vertical bore 37 and, thus, with the chamber 40 at 61. In its more outward portion the bore 62 may be of enlarged diameter and internally threaded; from the inner end part of the enlarged-diameter portion of the bore 62 a port 63 may lead diagonally through the housing 21 to the ambient. Partially into the outward portion of this bore may be screwed an externally threaded rod 64, from the inner end of which there extends inwardly a gradually tapered smaller-diameter and unthreaded extension 66 which with the shoulder formed between the inward and outward portions of the bore 62 constitutes a needle valve 65. The rate of bleed through the thus-described bleed path 60 may be regulated by adjustment of that needle valve, effected by rotation of the rod 64 as by a knob 67 externally secured thereon. From the more outward portion of the threaded bore 62 there may extend to the nearest face of the housing 21 a threaded hole 68 in which there may be positioned a set-screw 69 by which the valve 65 may be locked in any once-made desirable adjustment, or frictionally restrained but not locked, if preferred.

The pressure-induced upward movement of the diaphragm 41 which unlatched the actuator 30, for which the required pressure (over-atmospheric) in chamber 40 is predetermined at the sum of the adjustable downward biasing force on the diaphragm plus the force required to overcome the static friction mentioned above, will have carried the diaphragm to a position higher than its initial position illustrated in FIG. ltypically to a position of abutment of the top of flange 52 against the bottom of portion 43 of member 42and the diaphragm will not return downwardly even as far as the FIG. 1 position, much less both so return and re-develop an appreciable downward force of stud projection 57 on the full-diameter portion of plunger 32, until the pressure in chamber 40 has been reduced to a relatively small value (typically, for such return and force re-development, a pressure of the order of 20 mm. Hg); Until the decreasing pressure reaches that small value there is not possible a re-actuation of the apparatus.

To provide for as early as possible a re-actuation when required or desired, as well as in other cases to eliminate useless prolongation of interference with the patients circulation, the cycle mentioned above preferably further includes, as a portion ensuing the slow decrease of pressure within the chamber 40 and armlet 7, a final efiiux of gas from that chamber and member, of rate substantially increased over that of the slow bleeding-away; means for achieving such a final effiux, seen only externally in FIG. 2, are illustrated indetail in FIG. 4. Thus, inwardly from one of its six faces, for example the face opposite that from which the bore 62 extends inwardly, the housing member 21 may be provided with a medium-diameter horizontal bore 71 of which an inward upper minor portion intersects the vertical bore 38 and thus the chamber 40 and of which the outer portion may be internally threaded. Into this bore 71 there may be screwed a valve housing 72; this housing may be provided with a bore which for a substantial distance from the inner housing extremity may be of one diameter indicated as 73, for a short further distance may be of slightly reduced diameter indicated at 74, for a short still further distance may be of a further reduced diameter indicated at 75, and may finally be of a still smaller diameter indicated at 76.

Fitting and axially movable within the diameter 73, forming an element of a check valve 80, may be a plunger 81 into which from its outer extremity there may extend for most of its length a bore 82; within this bore, and extending from its inner extremity to the shoulder formed between the diameters 75 and 76, there may be compressed a helical spring 79 which biases the plunger 81 inwardly, normally into abutment against the inner extremity of the bore 71 in the housing 21. The outer end portion of the plunger 81 may be of diameter sufficiently reduced to fit freely within the diameter 74 of the valve housing, and between that end portion and its main portion the plunger 81 may be provided with a circumferential groove 83 of still smaller diameter. In the groove 83 there may be positioned a rubber O-ring 84; this O-ring will not create a seal between the plunger and the main bore portion 73, but will create a seal when compressed between the shoulders respectively formed between 73 and 74 and between groove 83 and the main portion of the plunger 81. The plunger 81 may be provided with a flat 85 ground longitudinally of its periphery (shown at the top) along which gas may be discharged at a moderate rate-substantially greater than the rate of bleed through the bleed path 60, whatever bethe adjustment of the needle valve 65, but substantially less than the rate of gas influx through the valve 14 when openwhenever the O-ring 84 is not compressed between the shoulders mentioned above.

The inlet valve 14 having been opened, then until the pressure within the chamber 40 and armlet 7 has risen sufliciently to displace the plunger 81 outwardly against its bias a moderate-rate discharge of gas from that chamber and member will occur along the flat 85. This will not be sufficient, however, to preclude a rapid build-up of pressure in that chamber and that member, and when that pressure has built up to a suflicient value it, acting on the inner end of the plunger 81, will displace the plunger leftwardly against its bias to result in compression of the O-ring 84 between the shoulders last mentioned above; such compression will stop the moderate-rate efllux previously permitted along the fiat 85. That moderate-rate efllux will remain stopped while the pressure within the chamber 40 and armlet 7 further rapidly rises to the predetermined pressure (defined above) for which the diaphragm 41 bias has been adjusted,'and thereafter while that pressure slowly dropsuntil it has dropped to that lower value at which it is no longer suflicient to hold the plunger 81 displaced against its bias. Then in response to that bias the plunger 81 will move inwardly and the moderate-rate efllux will be re-established. The moderate-rate-efllux-effecting means thus described and provided with numerals lying between 71 and 85 inclusive may be considered as a normally open check valve 80 closed in response to pressure within the chamber 40 and member 7 exceeding the value for which by the force of its biasing means 79 that valve is adjusted.

In the normal use and operation of the apparatus the unlatching of the actuator 30 by the diaphragm 41 at an appropriate pressure will preclude the development within the chamber 40 and the armlet 7 of excessive pressure. It is, however, conceivable that an improvident setting of the adjustor 50 or some malfunctioning of the apparatus might result in the development of an excessive pressure in those elements, and to preclude such development there may be incorporated within the housing 21 a relief valve. Such a valve, designated as 90, has been illustrated in FIG. 5.

Thus, upwardly from the bottom of the housing 21, for example closely adjacent one of its six faces not hereinabove specifically mentioned, there may be provided a medium-diameter bore 91 extending almost to the level of the bottom of bore 38, and from that level upwardly almost to the bottom of bore 39 there may be provided a coaxial smaller bore 92; the latter bore may be made to communicate with the chamber by a bore 93, in plan partially overlying the bore 92 and extending downwardly from the bottom of bore 39 to intersect the bore 92. The lower portion of the bore 91 may be internally threaded and into that bore may be screwed a sleeve 94 which extends upwardly to hold a rubber O-ring 95 between its upper extremity and the shoulder formed between 91 and 92. The lower end portion of the sleeve 94 may be solid excepting for a small central hole 96; within the sleeve, between that lower end portion and the O-ring 95, there may be sequentially assembled a compressed helical spring 97 and a ball 98 biased by the spring into pressure against the O-ring. The degree of compression of the spring 97 is so established that upon the development in the chamber 40 of more than a predetermined pressure the ball 98 will be forced against the bias of the spring away from the O-ring 95, whereupon gas may escape between O-ring and ball and through the sleeve and through hole 96 to the ambient, thereby precluding the development in the chamber 40 and armlet 7 of appreciably more than that predetermined pressure.

The operation of the apparatus, which may at the outset be assumed to be in the FIG. 1 and FIG. 4 condition of readiness for actuation, may be briefly reviewed as follows: The operator at will may press the actuator 30 (by its knob 31) whereupon it will be latched in the FIG. 10 position and the inlet valve 14 will have been opened. There will then occur a rapid influx of gas under pressure into the chamber 40 and armlet 7. During that influx there will occur a slow efllux of gas through the bleed path 60, but this eflects no significant reduction to'the net influx. During the early part of the influx there will also occur an efllux of gas through the then-open check valve 80 which effects an appreciable, but still typically minor, reduction of the net influx; when the pressure within 40 and 7 has reached the moderate value predetermined by the bias of that check valvetypically about 40 mm. I-Igthat check valve will close. The influx of gas will continue until the pressure within 40 and 7 has reached the higher value predetermined by the setting of the adjustor -typically any value selected by the operator in the range from about 100 to 240 mm. Hg. Then the diaphragm 41 will be moved upwardly by that pressure, unlatching the actuator which will thereupon resume its normal or FIG. 1 position, and the valve 14 will be closed and the influx of gas stopped. The gas flow will now be simply a slow net efllux from 40 and 7 through the bleed path 60. When this efllux has reduced the pressure within 40 and 7 to the moderate value predetermined by the check valve 80 that check valve will open, whereupon there is initiated an efilux through that check valve which is substantially greater in rate than that through the bleed path and which rather quickly drops the pressure within 40 and 7 to zero, the apparatus being restored during this quick drop to a condition of readiness for reactuation.

While the control device 20 may be positioned at any desired location, it is particularly convenient when it is to be used in connection with an anesthesia machine to mount it, as shown in FIG. 6, by means of a suitable bracket 102 to one of the corner posts 101 of that machine. When it is at a low position such as illustrated, the actuator knob 31 is well positioned to be pressed by the foot of the operator, or lightly kicked; alternatively, a higher position readily provides for actuation by the operators knee.

The connection in the system of the conventional hand bulb 8 with its bleed valve 9 (which will, of course, be kept closed during fully automatic operation) aifords the opportunity to superimpose on the automatic cycle described above any desired hand-effected modification of pressure, as well as at any time to use those conventional elements in temporary substitution for the automatic apparatus. Quickly to render those conventional elements fully operative in the remote event of rupture of the diaphragm 41 or the like, the end of the line portion 10" may be transferred from the socket 22 to a dead socket 23 (seen dottedly in FIG. 2) thereby closing the end of that line to result in a wholly conventional system.

If desired, there may be provided about the stud 56, between the nut 55 and the bottom of the bore 38, a compressed spring (not shown) which will itself bias the diaphragm 41 upwardly-it being understood that the spring 59 is then to be compressed (by suitable adjustment of the adjustor 50) by the additional amount normally required to annul the efieet of the added spring. The benefit of the added spring is simply that if during any period of intended nonuse of the apparatus the adjustor 50 be upwardly adjusted so as largely to relieve the compression of spring 59, the stud 56 will rise at least minutely from its FIG. 1 position, thereby precluding any latching of the actuator during such period of intended nonuse.

While I have disclosed my invention in terms of a particular embodiment thereof, it will be understood that I intend thereby no unnecessary limitations. Modifications in many respects will be suggested by my disclosure to those skilled in the art, and such modifications will not necessarily constitute a departure from the spirit of the invention or from its scope, which I undertake to define in the following claims.

I claim:

1. Blood pressure taking apparatus, for use with a pressurized source of gas, said apparatus including an inflatable armlet, pressure reading means connected to the arrnlet to monitor the pressure within said arrnlet during pressure excursions through systolic and diastolic ranges, a housing having an actuator mounted therein to be movable at will from an initial position to a flow position to initiate a rapid influx of gas into said arrnlet from said source, said actuator being releasably retained in said flow position, diaphragm means in said housing controlled by pressure within said armlet and rendered eifective when pressure has risen to a predetermined value at or above systolic pressure to release said actuator, means displacing said actuator from said flow position to its initial position to effectively terminate said influx of gas, restricted discharge outlet means in said housing providing a slow net efliux of gas from said arrnlet when said actuator is in its initial position, and a biased relief valve outlet in said apparatus controlled by the pressure within said armlet effective when that pressure has dropped to a lower 10 predetermined value at or below diastolic pressure to increase the said net efilux from said arrnlet.

2. The subject matter claimed in claim 1 wherein said relief valve means comprises a normally open check valve closed in response to pressure within said arrnlet exceeding said lower predetermined pressure.

3. Blood pressure taking apparatus for use with a pressurized source of gas, said apparatus including an inflatable armlet, pressure reading means connected with said arrnlet to monitor the pressure within said armlet during pressure excursions through systolic and diastolic ranges, a housing having an actuator mounted therein to be movable at will from an initial position to a flow position to effect a cycle sequentially including a rapid increase of pressure in said arrnlet and a slow decrease of such pressure, said actuator when in said flow position being releasa bly held in said position and biased toward said initial position, an inlet path connected with said housing through which when open gas may be rapidly supplied from the source to said armlet, said actuator in its initial position leaving said inlet path closed and when moved to its flow position opening said path, diaphragm means in said housing controlled by pressure within said arrnlet and rendered effective when that pressure has risen to a predeter-mined value at or above systolic pressure to release said actuator and allow it to return to said initial position thereby to return said inlet path to closed condition, and a bleed path open for the slow discharge of gas from within said arrnlet to the atmosphere to cause the pressure in said armlet to decline after said inlet path is thus closed.

4. The subject matter claimed in claim 3 further including means, also controlled by pressure within said armlet and rendered effective when the armlet pressure has dropped to a predetermined value at or below diastolic for increasing the rate of discharge of the gas then remaining within said arrnlet.

References Cited by the Examiner UNITED STATES PATENTS 2,070,661 2/1937 Hughes 137-463 2,275,534 3/1942 'Langsdorf 128-188 2,379,573 7/1945 Gilson 128-205 2,624,334 1/1953 Epstein 128-2.05 2,952,253 9/1960 Seligman 1282.05 2,980,107 4/ 1961 Hurley 128-205 RICHARD A. GAUDET, Primary Examiner.

LOUIS R. PRINCE, SIMON BRODER, Examiners. 

1. BLOOD PRESSURE TAKING APPARATUS, FOR USE WITH A PRESSURIZED SOURCE OF GAS, SAID APPARATUS INCLUDING AN INFLATABLE ARMLET, PRESSURE READING MEANS CONNECTED TO THE ARMLET TO MONITOR TO PRESSURE WITHIN SAID ARMLET DURING PRESSURE EXCURSIONS THROUGH SYSTOLIC AND DIASTOLIC RANGES, A HOUSING HAVING AN ACTUATOR MOUNTED THEREIN TO BE MOVABLE AT WILL FROM AN INITIAL POSITION TO A FLOW POSITION TO INITIATE A RAPID INFLUX OF GAS INTO SAID ARMLET FROM SAID SOURCE, SAID ACTUATOR BEING RELEASABLY RETAINED IN SAID FLOW POSITION, DIAPHRAGM MEANS IN SAID HOUSING CONTROLLED BY PRESSURE WITHIN SAID ARMLET AND RENDERED EFFECTIVE WHEN PRESSURE HAS RISEN TO A PREDETERMINED VALUE AT OR ABOVE SYSTOLIC PRESSURE TO RELEASE SAID ACTUATOR, MEANS DISPLACING SAID ACTUATOR FROM SAID FLOW POSITION TO ITS INITIAL POSITION TO EFFECTIVELY TERMINATE SAID INFLUX OF GAS, RESTRICTED DISCHARGE OUTLET MEANS IN SAID HOUSING PROVIDING A SLOW NET EFFLUX OF GAS FROM SAID ARMLET WHEN SAID ACTUATOR IS IN ITS INITIAL POSITION, AND A BIASED RELIEF VALVE OUTLET IN SAID APPARATUS CONTROLLED BY THE PRESSURE WITHIN SAID ARMLET EFFECTIVE WHEN THE PRESSURE HAS DROPPED TO A LOWER PREDETERMINED VALUE AT OR BELOW DIASTOLIC PRESSURE TO INCREASE THE SAID NET EFFLUX FROM SAID ARMLET. 